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Wed, 13 Feb 2019 04:37:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nxp.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=OHY+UnclL6nMroYOgKgCycsfT7iOg0Cv6WyGM/vERMU=; b=rjK8siTZgySl54xE9iPLDnM7ng5P5OfZbyb1AuuAYUtzIxYCwhRWtDE2kDddA64yMAE27/oBEZOZgsfXMLGSRo0htONAptTMu0F0LeHeaVrM74pbSO+Y9otC8IOU2S7n2rwarAcUAX1uFGQrg82U0GKFzDsg5MdVbkTx4m27W2w= Received: from DB7PR04MB4490.eurprd04.prod.outlook.com (52.135.138.16) by DB7PR04MB5148.eurprd04.prod.outlook.com (20.176.235.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1601.22; Wed, 13 Feb 2019 09:37:39 +0000 Received: from DB7PR04MB4490.eurprd04.prod.outlook.com ([fe80::fd45:a391:7591:1aa5]) by DB7PR04MB4490.eurprd04.prod.outlook.com ([fe80::fd45:a391:7591:1aa5%6]) with mapi id 15.20.1601.023; Wed, 13 Feb 2019 09:37:39 +0000 From: Peng Fan To: "catalin.marinas@arm.com" , "will.deacon@arm.com" , "mark.rutland@arm.com" , "ard.biesheuvel@linaro.org" , "yaojun8558363@gmail.com" , "cpandya@codeaurora.org" , "robin.murphy@arm.com" CC: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "van.freenix@gmail.com" , Peng Fan Subject: [PATCH 3/3] arm64: mmu: pgd_pgtable_alloc: drop barrier Thread-Topic: [PATCH 3/3] arm64: mmu: pgd_pgtable_alloc: drop barrier Thread-Index: AQHUw3/CYobPCtINwEOlvcbOdnGfRg== Date: Wed, 13 Feb 2019 09:37:38 +0000 Message-ID: <20190213094831.7292-3-peng.fan@nxp.com> References: <20190213094831.7292-1-peng.fan@nxp.com> In-Reply-To: <20190213094831.7292-1-peng.fan@nxp.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: git-send-email 2.16.4 x-clientproxiedby: HK0PR04CA0013.apcprd04.prod.outlook.com (2603:1096:203:36::25) To DB7PR04MB4490.eurprd04.prod.outlook.com (2603:10a6:5:35::16) authentication-results: spf=none (sender IP is ) smtp.mailfrom=peng.fan@nxp.com; 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received-spf: None (protection.outlook.com: nxp.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: cmWn6KbHSsfZN/LXGmvYr8MlPEN+I/oWp8NJwZUCZSTVfvIEkaTul0xDagFsoIjyyZTYxypla9HHGg/fYl17s5QF8EVn66VHzkLbFHy/3piq8fVuP0uOAmimr6LGbxH/mMLOoXecDgAnW6Nq1QAZzrCKeEgV77PH/jy+GWTSvIWQZTTYU3/xPuoSEdH9o5SSGHajsA+k/A9uq2qt51fPsvUWsyAlmzQxmbXAasKPmXVi2iS1XcN0wWpyJ/R0LjAEZvvaC4GP2CjiPlmJ0NRrgvxzjUbpYT4p1PSvURNRYqZ89VUR2j8bdUD6AbuGb4fve+FWrLYjFGYsmXDpytALpZy9COU+yYJjFQxV+pLMkbmHKTBlMn+HTWIbjGdinzEX7VcROUbbB2owtFnYIdScY8CJgxkcQTd3/XsV4w2aIzI= Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6d774fe4-9005-4b02-3c44-08d69196e157 X-MS-Exchange-CrossTenant-originalarrivaltime: 13 Feb 2019 09:37:29.3459 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR04MB5148 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The barriers are added for empty_zero_page, however the empty zero page has been moved to bss area by commit 5227cfa71f9e ("arm64: mm: place empty_zero_page in bss"), and it alreay added "dsb ishst" in head.S to make sure the empty zero page visible to PTW. pgd_pgtable_alloc is only called by __create_pgd_mapping, and there are implicit barriers in __create_pgd_mapping, so we could remove the barrier pgd_pgtable_alloc Signed-off-by: Peng Fan --- Note: this patch tested on qemu-system-aarch64, not real hardware. arch/arm64/mm/mmu.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index f61fa7c8fd2e..04e3d4d070ce 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -371,8 +371,6 @@ static phys_addr_t pgd_pgtable_alloc(void) if (!ptr || !pgtable_page_ctor(virt_to_page(ptr))) BUG(); =20 - /* Ensure the zeroed page is visible to the page table walker */ - dsb(ishst); return __pa(ptr); } =20 --=20 2.16.4